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Internal Combustion Engine Provided With Supercharger.

The present invention relates to an internal combustion engine of the kind set forth in the preamble of the following patent claim 1.
In internal combustion engines of this kind a compact design of the supercharger and the clutch means and associated parts is aimed at. An electrically controlled clutch means has the advantage of having slight space demand and has proved useful for most applications of this kind.
A drawback is, however, that the useful life has proved limited due to especially overheating in connection with frequent engagements and
Hydraulically controlled clutches are reliable but have larger space demands and also an oil pump driven by the engine.
The object of the invention is to provide an internal combustion engine of the kind mentioned above in which the described drawbacks are completely or partly eliminated. This is achieved, according to the invention, in that the internal combustion engine has obtained the features stated in the characterizing clause of claim 1. Primarily, the lubricating oil system of the internal combustion engine is utilized as a pressure fluid source for a hydraulic clutch for engagement and disengagement of the supercharger such that the need of a special oil pump for the hydraulic clutch is eliminated.
A particularly compact and reliable design is set forth in claim
2. In this design the clutch is built-in in an end cap of the supercharger with the cylinder chamber shaped directly in the wall of the end cap. At the assembly of the supercharger only a pressure pipe for lubricating oil has to be attached between an outlet in the wall of the engine and an inlet in the wall of the supercharger.
The invention is described in more detail in the following with reference to the attached drawing schematically showing an embodiment of the internal combustion engine according to the invention chosen as an example.
The drawing shows an internal combustion engine 1 and a supercharger 2, shown in longitudinal section, mounted to the engine. The crankshaft of the engine carries a belt pulley 3, which via a belt 4 drives a belt pulley 5 of the supercharger. This is of the screw compressor type and has two in a housing 6 rotatably journalled screw rotors 7,8. The rotor 8 has a driven shaft 9, which via a disc clutch 10 is engageable to a driving shaft 11 to which the belt pulley 5 is secured.
The clutch 10 is a disc clutch of the type shown in detail in SE 9501501-2 and in the application named "Transmission including a two part clutch arrangement" filed at the same time as this application and to which reference is made as to the operating of the clutch.
The clutch is built-in in an end cap 12 which is secured to one of the end walls of the housing 6. A cylinder chamber 1 is designed in the interior of the end cap 12, in which chamber an annular piston 15 is axially movable towards the clutch means 10 for pressing a pressure plate 16 via a thrust bearing 17 against the discs of the clutch. This is obtained by supply of a pressure medium to the cylinder chamber 14.
For that purpose there is an opening 18 in the wall of the end cap 12, which opening 18 is connected with an outlet opening 19 in the wall of the engine 1 via a pressure pipe 20. The pressure side of an oil pump 24 is connected with the outlet opening 19 directly or via the lubrication system of the engine.
Engagements and disengagements of the clutch is performed by means of a valve 21 connected in the pressure pipe 20, which valve is controlled in dependence of the load of the engine in a manner known per se, which here is shown by a control means 22 connected with a foot accelerator pedal 23. Normally the valve 21 is also controlled by the electronic control-system of the engine (not shown).
The invention is of course not limited to the embodiment here shown and described but can be modified in various ways within the scope of the inventive idea defined in the patent claims. Particularly the control means of the clutch designed in the shape of a piston 15 and a cylinder chamber 14 may, as an alternative, be designed as a membran.